comparing 2 DACs with BNC T-connector?

In a logical yes/no way: yes, this will work. But in order to make a fair comparison, please take the additional hassle of unplugging every time, that's the only way to make a fair comparison.

You won't blow anything up - it just won't allow you to get the best from either DAC. Stick to one plugged in at any time (from digital source and to pre-amp)

James

As James has said. Also, make sure to exactly match volume level when comparing

Thanks! Technically, do DACs provide a significant 'load', so that 2 DACs (possibly even with different 'loads' ) sitting on the same digital source, can influence each other (asymmetrically)? Isn't it just bits?

I realise that I only (roughly) understand analog loads but have no clue about the digital domain! thus, any further comments would be welcome!

S.

Stefan, just swap the cable over at the end of listening to each unit.  Even if there were no deleterious effect of using a T connector it would only encourage you to try flicking back and forth between each unit - a sure recipe for missing the sometimes subtle yet critical differences in performance.  The only way to make a valid comparison is to play a piece or pieces of music through on each unit in turn.  Don't analyse too much or focus on the cosmetics - the brain naturally begins to compare things like bass, mid, treble etc.. - instead just relax and let the music play. Choose the one that allows the music to engage you the best and make most sense.

Stefan Vogt posted:

Dear all,

may I connect e.g. the digital output of the NDX to 2 DACs (say, Hugo and 2Qute) in parallel (using a BNC T-connector and branching out from this to the 2 DACS), or would I always have to unplug one DAC and plug-in the other DAC when making comparisons, please? The T-connector would be convenient, and I'm also curious if this works, but obviously I don't want to blow-up anything, thus most grateful for your advice!

Many thanks,

Stefan

Stefan, you can do this, and it should work, as SPDIF is not duplex, i.e. It's one way only... however you may end up pushing the SPDIF transmission outside it's designed operating guides because of imperfections in the sender/receivers, so you may get more jitter/smear in the transport or even more errors... (resulting in a 'tick' or brief silence)

Now yes if the the sender and the receivers are designed with a perfect 75ohm characteristic impedance then yes this  setup should be fine, but I doubt they really are... also if you have a T connector, you should really put a 75 ohm terminator across an unused connection so as to avoid reflections... SPDIF isn't hyper critical and goes over short lengths in most home setups, so you can probably get away with a multitude of sins... but I would check carefully for SQ impact.. and remember DACs are lossy/inexact in the limit.. .. they have their own characteristics. So if comparing listen to some music on one.. finish, go have a cup of tea or similar, and then come back and listen to the other.. that way you won't confuse the brain.. your brain will adjust to each presentation...

And yes there is also the issue of grounds... if you were sharing the line you would need to ensure all coonections were galvanically isolated so as to avoid ground issues... remember SPDIF is unbalanced... I don't think the Chord devices galvanically isolate their SPDIF... but if all connections are isolated and only one, say the Chord, isn't it should matter at all.

Thanks, Simon, this helps.

In fact, I encountered (mild) ground issues when having swapped one cable whilst the other was yet unswapped (sorry, I should have always disconnected all cables first).

S.